Sound-intensifier.



A. NIKIPOROPF. SOUND INTENSIFIER. APPLICATION FILED Nov. 21, 1907.

920, 624. Patented May 4, 1909.

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ALEXANDER NIKIFoRoFF, or winsiw, Russia.

SOUND-INTE NSIFIER.

Specification of Letters Patent.

Patented May 4, 1909.

Application filed November 21, 1907. Serial No, 403,181.

To all whom 'it may concern.'

Be it known that I, ALEXANDER Nini- Fonoiri, functionary, a subject of the Emperor of Russia, residing at Marszalkowska 36 W. 3, Warsaw, Russia, have invented new and useful Improvements in Sound- I-ntensiiiers, of which the following is a specication.

My invention relates to an electric sound intensifier more particularly adapted for -telegraphy and telephony, both on the wireand Wireless systems.

It has reference generally to means for amplifying telephone currents and feeble alternating currents of variable frequency.

Prier electric sound intensiiiers have con sisted of appliances not more sensitive than a telephone receiver, and have been such that it has only been possible to intensif relatively strong currents with them Witli my new invention, on the contrai' even currents too weak to be heard in a te eplioiie receiver can be intensified to any' desired extent. As is well known, the receiver has been regarded as the most sensitive a paratus existent within the range of smal cur-l` rent electrotechnics.

According to my invention an annular armature is carried by a stretched loop and f isunder the influence of hollow concentric vpole pieces separated from the polarization l. source by an air-gap containing a magnetic i'ield, the said armature by means of a pin acting upon an electrically independent microphone is held automatically in contact 'with it, the microphone diaphragm or memi ly damped by the'aforebrano' being suite said E austivev experiments have shown that by means of this appliance sounds, such as music and conversation, can bc very essentially magnified. also be used, for instance, for intensifying alternating currents of various fre uencies,

,n such as are employed in wireless te egraphy g and telephony, etc., when the sounds transmitted are not sufficiently well heard, or are not loud enough to perform mechanical work. Y

My inventionis illustrated in the accompanying drawing, in which- Figure 1 is a longitudinal section through a form of construction of the new apparatus. Fig. 2 is a front elevation of the microphone.

Fig. 3 is a rontelevation of the apparatus, l

The new apparatus can i the microphone being removed. Figs. 4, 5 and 6 show modiications of the microphone i device. v i The construction shown in Figs 1-3 is the i result of practical ex erinicnts, but it vmust jbe understood that in no wise desire to restrict myself to such, since the principle of the invention can be employed in various ways.

Referring to Fig. 1, the polarizing circuit 1, I which contains a source oi' electricity 2 (such l as a single cell) is connected to the ends ol' i the coil 3 of a so-called iron-clad or bell elecy tromagnet, consisting of two concentric hollow poles 4, 5. To hold thc coil 3 a vulcaniti` or otherI suitable ring 6 may be employed. Opposite the ends of the poles 4, 5 there 'are located the hollow poles 7, 8 (each divided longitudinally into four parts in order to 'pre- Vent the formation of eddy currents) of a second magnetic device. The distances be- 1 tween the ends of the poles 4, 5 and those of the poles 7,8 can'bc regulated. The line circuit 9 is connected to the coil oi thi` hollow pole magnet 7, S, the wires being advantageously conducted through pcrfoi'ations in a brass ring 10.` For securing' thc segments ol' the four-part hollow' poles 7, S a screw collarl s to the pole 4. At the top and bottoni of thc yoke 12 there is secured a bracket having two l lugs 13 which servo to guide a sliding niember 14, which can be raised or lowered as dcsired by means of set-screws 15. The slides 14 are rounded outwardly and serve to hold a i wire loop 16 having the shape ol an elongated l O. This loop is provided centrally with a brass ring 17 having a disk .1S of dianiagi netic material. This disk 18 is provided with a pin 19 of steel or 'other hard material, directed outwardly and having a rounded end. The brass ring 17 carries an iron arni ture 20 of several, for example four segments. i The number of armature segments correl spends With that ci the number of the poles 7, 8, the division into segments being for the brass yoke 12, screwed or otherwise secured' scones i purpose of avoiding the formation ot' eddy I pieces, which are separated from the polarcurrents. Against the rounded end of the pin 19 there bears with a certain regulable pressure the movable part ot' a microphone, This part is shown as a diaphragm in Figs. 1 and 2, but may be in the form of a spring or otherwise, such for instance, as shown in Figs. 4, 5 and 6.

The microphone case shown in Fig. 1 is mounted to oscillate on an axis, located in the top part of the yoke 12, so that the case may come into contact with the vibrator of the magnet system autoinatically.K The arrangement may advantageously be such that studs 38 are screwed through clieekieces ,of the yoke 12 and provided with smallpdepressions or "pops to receive the centers or points of a short axis 21 (Figs. 1 and 2). i

Pendant from the latter is an arm 22, which carries the microphone case 25. rlhe microphone is of the Well-known granulated carb on type, 'the carbon particles being contained in a suitably shaped carbon slab 23 at the bot# tom of the case 25. The slab is surrounded by a felt or other suitable jacket having the .form of a hollow truncated cone, Whose Outer edge lies against the. carbon or like suitable diaphragm 24, secured in the case, and, as

. already mentioned, rests against the rounded end of the steel pin 19. v The space between i the diaphragm and the carbon slah 23 is filled saine (Fig. 5) 5 alteration in the intensity of with carbon granules in Well-.known manner. The slab 23 is insulated from the case k2.5 in any suitable Way. 'ln order that the pressure With which the diaphragm 24 bears upon the pin 1Q may be regulated, a screw spindle 2.7 may be provided at the top of" the arm 22, and a counterweiglit 2G furnished upon the spindle, so that by screwing this Weight in one direction or the other, thc pressure ofthe dianhrfi can be adjusted. The conductors 2o, limoni` ceiver 8O of any ordinary lescription, may be connected to 'the Ycase. 25 at any suitablel parts. ln the receiver circuit a cell or battery 29, or any other well-known source of' moved over a reducing rheostat 31, so that [the microphone is set in. action.

accordingl I' as the end 1 lies more or less to the right or lett, more or resistance is cut into the circuit and in consequence the attractive force, or degree of' polarization of the magnet 7, 8 filtered.

The apparatus is set in action by the line current, which flows through the coil of the hollowv pole-pieces 7' and 8 'whereby the trembler and thereafter the movable part of By the novel arrangement the effect of the current is increased by reason of the coil being into a telephone re' izing source by an air gap. The formation of eddy currents is prevented on account of the above mentioned construction and ofthe 'total division or splitting up of thepolepieces as Well as of the armature. y

The construction of the present sound-intensifier is'the vresult of the researches of the applicant in the domain of electro-magnetism vvhich demonstrated- 1. That the polarization of the magnetic and predominates near the contours of the pole piecesection.

3. That the distribution of the lines of force in the magnetic field of a coil presystem ofa relay cannot bemaintained absoeminently takes place near the contours or outlines, essentially owing to the fact that a part of the iluX passes through the copper and thus practically disappears.

Instead of the regulating Weight 26, especially When very great accuracy is required, an electromagnetic device might be employed for the microphone case also. `This device might consist of an iron core secured to an arm, and of a solenoid embracing the the current flowing to the solenoid can then be effected by insertingmore or less resistance in the circuit, in Well-known manner, ln this Way the diaphragm of the microphone Will be pressed With more or less force against-the pin 19. The advantage of this method is that the pressure of the diaphragm can be regulated from a distance, which is much inoreconvenient than having to adjust by hand, as regulation must be effected during operation of the apparatus.

The microphone diaphragm may be replaced by a Wire loop, whose construction corresponds with that of the vibrator of the magnet system. ln order that the diaphragm may be rendered more sensitive, it

may be cut away circumferentially at 89' ishould also be remarked that the microphone diaphragm requires no damping, such as is necessary With ordinary microphone cases, for damping is eilected bythe pressure of the pin.

ln the modification shown 1n Fig. 1 the arm 22 is furnished in frontwith an arm 33- closed between the tac concentric polel carrying a small hammer 32, which may consufficiently small to prevent the very minutel granules of carbon Afrom falling out of the case. The modiication shown in Fi 6 is similar, but a carbon disk 36 is emp Oyed, adhesively attached to a felt ring 37. No spring is necessary in this case.

A single device of the above descriptionis suiicient to greatly intensify the smallest sounds or current impulses, which can be heard in the best receiver, but the efect can naturally be increased as required by the employment of a number in common.

Having tilusdescribed my invention, what- I claim as new is:- i

. In an apparatus for intens' tele- ,phone and like electric currents an alternatmg currents 4of variable frequency, the combination of anannular armature, a pin fixedA to said armature, 4a stretched loop ca g said armature and pin, concentric hoow pole-pieces acting upon said annular armature and forming a magnet system excited by the currents to be'amplified a polarization source the said pole-pieces being each separated from the polarization source byan' airgapv containing a magnetic. field, and a microphone system influenced b Athe armature through the medium of sai pin, but freely' regula suspended and electric-ally independent of 'l the said pin, substantially as set forth.

2. An electric sound intensifer, comprisin a magnet' system possessing concentric ho low poles and lpresenting a movable art con -sisting di an armature and a stretc ed wire loop carrying the same; and a microphone havina movable part bearing with a certain art of the magnet system; substantially as escribed.

3. In anapp'aratus for` intensiying'tele-i phone and like electric currents, the combination of a polarization source compr' twohollow and concentric oles excited y Aa current capable of regu ation, a magnetic system consisting of two hollow and concen-v -tric poles inclosing between them thecoil receiving the line current, 4the said poles, which are separated from the source of polarization by an air gap, 'which contains a' Imagnetic field, beingcompletely dividedlongitudinally, and of a vibrator formed of a stretched wire loo carrying a radially divided or s lit an- -nu ar-armature arranged in front of t e said oles and being provided with a central pin or transmitting-vibrationsto a microphone s stem which is automatically damped by the ressure of the said'pin, substantially as set orth' In witness whereof I have hereunto signed my name this fourth day of November 1907 in the presence of two subscribing witnesses.

ALEXANDER NIKIFOROFF.

Witnesses:

HERNANDO Dn Soro,

WrroLD Fuons.

le pressure against the said movable' 

